According to the disclosure of Japanese Laid-Open Patent Publication No. 2005-206371, a transfer apparatus of an overhead traveling vehicle moves toward one of the left and right sides of a traveling direction for allowing an article to be transferred between the transfer apparatus and a buffer provided on a side of a travel rail, i.e., a side buffer. In Japanese Laid-Open Patent Publication No. 2005-206371, though the transfer apparatus can move the transfer apparatus only one of the left and right sides, if it is possible to move the transfer apparatus toward both of the left and right sides, for example, the following advantages can be obtained.    (1) It is possible to additionally provide side buffers, in particular, at a position above processing equipment or the like.    (2) It is possible use a side buffer at the center by overhead traveling vehicles on the left and right sides of the side buffer.
For this purpose, it is necessary to increase the length of the stroke, assuming that directions of the lateral moment are both directions to the left and right. However, a mechanism required for achieving movement to the directions to the left and the right is complicated. Further, since high rigidity is required for the long stroke, the thickness of the mechanism for lateral movement (hereinafter referred to as the “lateral drive”) is increased. As a result, the size (height) and the weight of the overhead traveling vehicle are increased disadvantageously.